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New Member

People in Europe

I'm interested to know how people in Europe are installing their Call Manager environment. Specifically, how alaw and ulaw are handled. Is it alaw everywhere (IPphone-to-IPphone, IPphone-to-gateway, IPphone-to-Unity, etc...) ? Do you use the CM ulaw default and let the gateway do the conversion ?

Can somebody educate a US person to understand all this ?




Re: People in Europe

I too always wondered how is it done in Europe in general. I guess, the method that you guessed makes sense and easy to administer too. Can any user in Europe enlighten us if you follow some other strategy?

But I understand there are some limitations- using alaw with CRA.

Re: People in Europe


All the implementations that I do I leave as uLaw internal. there is no real benefit apart from the comfort factor in trying to change to Alaw.

On early installations I used to worry over compatability issues and set every gateway to Alaw, but on the basis that the phones would then use ulaw anyway I stopped.

So far I've not come accross any problems.


New Member

Re: People in Europe

Hi Justin,

I participated in many installations and we always leave the incoding to ulaw. It is only for external connections that the gateway will convert this to the necessary alaw encoding. I have only met 1 guy who claimed he could hear the quality degradation after converting from ulaw to alaw.(my ears can't)

It would be possible to change the default encoding to alaw but I really don't see a reason to do this so I advice my customers to stick with the defaults.


Steven Lauwers


New Member

Re: People in Europe

We currently use G.729a for all standard voice calls due to bandwidth issues. We connect to PSTN Via a PBX then a microwave link to the site where CM is installed:

PSTN <--> (ISDN Dass2) PBX <--> Q.931 to router <--> Microwave link (10Mb) <--> CCM

We have a back link that runs at 512K only. Due to the concerns of the backup link we decided to go with G.729a.

We have recently setup a new region that runs G.711 for conferencing and transcoding on Cat 4006 AGM Blade due to no support in software on CCM for G.729a. Faxes also use G.711 and everything seems to work ok.



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